It is well known in the prior art to utilize a dry toner or a powdered ink to dust the charged surface of a sheet of paper which has been electrostatically charged and then discharged by a beam of light, for example, reflected upon the surface of the paper. After the charged surface is discharged, the paper is exposed to the toner which adheres to the remaining charged areas. The paper is then exposed to a fuser which heats the toner to melt it into the paper and permanently affix it thereto.
Two electrophotographic processes are well known. The first, known as xerography, utilizes a photoconductive insulating medium which is exposed to electromagnetic energy such as infrared, visible or ultraviolet radiation. The charged photoconductive medium, which may be a selenium coated drum, is then dusted with a toner which is next transferred to a sheet of paper. The toner is then fused to the paper by heat. A second method utilizes a zinc-oxide-coated paper which receives an electrostatic charge and is discharged by electromagnetic energy directed upon the charged surface. The toner is then applied to the paper and fused as in the xerographic process.
Whether the electrophotographic recorder utilizes a selenium coated drum or zinc-oxide paper, the requirement to properly expose a surface to a desired amount of toner remains unchanged. Further, the need to uniformly apply the toner to the surface without creating voids within the toner also remains.